The present invention is directed to a system for providing IP (Internet Protocol) telephony transport having an in-line power back-up at a customer site, using the existing twisted pair infrastructure usually made of a conducting material such as copper. Internet protocol as used herein means the exchange of communication and information between computers and various terminals such as in this case, telephones, in a network environment. The existing twisted pair copper infrastructure, is presently used for connecting analog and digital phones, hereinafter also referred to as traditional telephones, to a traditional PBX (telephone voice switch). This twisted pair copper infrastructure uses a lower grade cable. The claimed invention on the other hand, allows the connection of new IP telephones to an IP PBX (Internet Protocol based voice telephony switch) using the twisted pair copper wiring, by introducing a twisted pair broadband switch, hereinafter TPBS, and a media converter, also referred to as MC. Currently, in order to connect a computer or an IP telephone to an IP PBX, a higher grade cable is required which is different from the twisted pair copper wiring. The difference between an analog, digital and IP (internet protocol) telephone are described below. Analog telephones are also referred to as plain old telephone or POTS. These are the commercially available phones used in business and in residences and these can connect to various vendor switches. Digital phones are an upgrade of the analog phones which uses digital transmission of sound and these phones have advanced features that are not present in analog phones. Digital phones are proprietary to a particular vendor's voice switch. A digital phone from one vendor can not connect to a phone switch from another vendor. IP phones are more advanced than either of the analog or digital phones and these phones can connect to any Ethernet based interface to be part of a LAN (local area network) or WAN (wide area network) and use standards based IP technology. Because of the use of standard technology and protocol, IP telephones from one vendor may be used with telephone switches from another vendor.
Traditionally, voice and data have been running on separate physical networks, both within and outside the customer premises.
Traditional voice networks comprise of a PBX (voice switch), which handles call control, feature delivery and power delivery to the desktop telephones. A dedicated pair of wires 2 which terminate on a line card of the PBX, as shown in FIG. 1, comprise of the connection between the PBX and the analog or digital phone which is located at a user's desktop. This traditional telephony system is still used worldwide. These voice networks usually run over a lower grade cable such as Categories 1-3 (CAT1-3) cabling. The PBX switches have battery backup to ensure operation of the PBX during power outages and also provide power to the Analog or Digital Telephones through the PBX, over the copper wiring. Operation of the telephones during times of crises, especially when the building electrical power is impaired is a must for continued availability and operation of the phone system.
Within the last few years, data ran on Local Area Networks (LANs) within the customer premises. This network consists of various technologies including Ethernet, Token Ring, and ATM. Today Ethernet has emerged as the dominant LAN technology and has the greatest market share. The physical wiring that is required to run Ethernet is different from that used with the voice network described above. It is usually done with Category 5 (CAT5) cabling which is widely deployed within buildings. In the LAN, a computer is typically connected to a data switch or a router through CAT5 cabling which carries the Ethernet traffic. Networks transporting data such as LAN are typically not provided with battery backup, and therefore, are rendered dysfunctional in the event of power loss.
There has been a push towards convergence i.e. using the data network to transport voice. This is due to the fact that data traffic volumes have exceeded voice traffic and enterprises stand to save money by sending voice on data networks. Convergence is happening at the network level as well as at the applications level and IP has emerged as the dominant protocol. A vast majority of the enterprise LAN traffic uses IP and it is a natural choice that voice should also be transported over IP. Consequently, there has been a huge industry focus on VOIP (Voice over IP) as is evidenced by the number of product offerings by existing vendors and the amount of venture investment on new VOIP startups. Convergence of voice and data on the same network and technology can be expensive, and maintenance personnel have to learn new technologies and procedures to manage the converged network.
Additionally, data traffic and voice traffic not only have conflicting requirements for the underlying network, but such sources are intrinsically different. Data traffic sources are bursty in nature and typically consume large amounts of network bandwidth. On the other hand, voice is a very well defined source in terms of bandwidth usage as it is constant bit in nature i.e. when a voice call is active it consumes 64 kbps (on a time division multiplexing, TDM, network) of bandwidth for the duration of the call. Although voice is not bandwidth intensive, it is extremely sensitive to delays. Voice as an application has severe problems when delays are beyond certain threshold values and if network delays exceed beyond a certain point, voice conversation may become impossible. The first problem associated with delay is the appearance of echo which modern DSP (Digital Signal Processor) technology has solved with the introduction of echo cancellers. However, if delays become too great, user conversation collisions are possible and communication may become downright impractical (user might have to use “over” to hand over control to the other side). The voice problems anticipated with convergence lie somewhere in the middle, i.e. there isn't much perceivable echo, nor is there collision, but voice quality is choppy depending on the prevailing conditions on the network, a condition not suitable for conducting day to day communications. If voice and data share the same data network and enterprises have not spent the resources to make the LAN “voice ready”, then users will experience this patchy voice performance.
Current systems carrying both data and voice traffic over the same wiring is shown in FIG. 3. LANs have historically been best effort networks and grew without any consideration given to QoS (Quality of Service) for handling delay-sensitive traffic like voice. At the time of inception no one had envisioned that someday LANs might be called upon to carry voice. During the last ten years there has been an astronomical growth in LAN traffic and this growth has mostly been “uncontrolled” i.e. corporations have installed LAN equipment to cope with the immediate need of accommodating increased data traffic without much thought given to performance guarantees. This has been acceptable because most LAN protocols are not delay sensitive and have recovery procedures at higher layers. They are concerned with information integrity, and getting information to the destination within reasonable time. LAN networks can tolerate delays that are of the order of seconds (even tens of seconds).
Until recently, providing timely delivery of voice traffic to the end-points was an issue as there was no way of ensuring QoS on a customer's LAN; when voice and data shared the network, traffic was switched on a first come first served basis. This set up is unsuitable for transporting voice over a LAN. The IEEE 802.1 committee released two specifications—802.1p and 802.1q, which allowed LAN hubs, switches and routers to prioritize traffic based upon the priority markings in an Ethernet frame. IEEE stands for Institute of Electrical and Electronics Engineers, Inc. which is a non-profit, technical professional association that releases various specifications on devices or equipment used in the field. While this solved the QoS issue, it is cost prohibitive for most legacy LAN networks. In order to get a prioritized LAN, it is required that enterprises swap out their old hardware and replace it with hardware that supports IEEE 802.1p and IEEE 802.1q. It is possible to undertake this upgrade in small enterprises, as the number of network elements that require swapping is small, however, in a medium to large enterprise, this could prove to be a daunting task, both from a cost standpoint as well as the disruption it causes to the data network and the overall business operation. If the upgrade goes awry, this has the potential of bringing the customer's entire voice and data network down.
Another problem that has prevented wide scale deployment of IP telephony is the fact that there is no true solution to providing in-line power to IP phones. Traditionally analog and digital phones have been powered from the central PBX, which in turn was battery backed up. The real reason for providing in-line power to phones in traditional PBX systems was to ensure that the system stayed up for a certain amount of time even when power to the facility was lost. The IP phone community is working on a standard called IEEE 802.3af, which defines a way of providing in-line power to IP phones through the un-used wires in the Ethernet wiring scheme. In practical deployments, IEEE 802.3af based equipment is placed in the data closet and provides in-line power to IP telephones. This solution gives a false sense of comfort to the customer that the IP phone is as resilient as the traditional telephones used to be. In fact, during a power outage, the data LAN goes out and consequently, voice connectivity goes out with it. To solve this issue, the enterprise customer has to provide battery backup for power to each and every LAN hub, switch and router. For IEEE 802.3af to be effective, it will require building a new battery backed power facility for the entire Data LAN. This may prove to be extremely expensive and in most cases may not be possible. In a brand new facility, this can be part of the planning process and the building can be designed with DC power to every data closet from day 1. However, there are only a few of these “Greenfield”, that is, new installations.
Another concern voiced by IT (Information Technology) professionals is the lack of security on VOIP systems. An experienced hacker can connect a laptop PC to any Ethernet Wall-Jack in the building and record conversations long enough to break the code and subsequently listen in on all conversations. In the traditional phone system, a hacker had to have access to the physical wiring of the building at the MDF (Main Distribution Frame) to physically tap into the phone network to listen to conversations. In a normal business environment where thousands of wires run through, this is almost impossible, and access to the MDF is restricted.
It is therefore an object of this invention to provide an IP telephony system that can transport voice without experiencing delay in the voice transmission or transport.
It is an object of this invention to provide an IP telephony system using the existing twisted pair infrastructure.
It is also an object of this invention to provide an IP telephony system with in-line power, the source housed at the same location as the battery back up of the PBX, to ensure that the system is operational during building power outages.
It is a further object of this invention to provide an IP telephony system that is secured from unauthorized access.